"The only thing we are trying to do is warn them of the risks they face and where to get water, so they don't die," said Mauricio Farah of the HRC.

But a spokesman for the US homeland security department said maps would not improve safety for those trying to cross the border.

"It is not helpful for anyone, no matter how well intended they might be, to produce road maps that lead aliens into the desolate and dangerous areas along the border, and potentially invite criminal activity, human exploitation and personal risk," said Russ Knocke.

Each year thousands of Mexicans breach the frontier and attempt to cross the parched Sonoran Desert.

Some 500 died last year while making the journey, the HRC said.

Last year the Mexican government issued comic-book style pamphlets warning of the dangers of illegal migration, while also giving advice on how to stay safe.